var fs = require('fs');

function changeVersion(path) {
    fs.readFile(path, 'utf8', function (err, data0) {
        if (err) throw err;
        var csstag = "([\\d\\.]+)rem";
        var regcsstag = new RegExp(csstag, "g");
        var css_result;
        while ((css_result = regcsstag.exec(data0)) != null) {
            console.log(css_result);
           data0 = data0.replace(css_result[0],Math.round(css_result[1]*75)+"px");
        }

        fs.writeFileSync(path,data0);
    });
}

changeVersion("./sfbmall.css");